1. Field of the Invention:
This invention relates generally to a hinged hood apparatus for covering a front engine room of a vehicle and, more particularly, to a vehicle hood apparatus arranged such that when a vehicle employing the hood apparatus collided with an obstacle while running, it mitigates the collision impact applied to the obstacle.
2. Description of the Prior Art:
When an obstacle Is hit by a running vehicle, the obstacle is often hit first by a front bumper of the vehicle, flown up and then landed on the hood. At this time, the obstacle is imparted with an impact of collision with the hood.
For mitigating such a collision impact, a vehicle hood apparatus is proposed in Japanese Patent Laid-Open Publication No. HEI-9-315266. The proposed hood apparatus is arranged such that upon collision, a rear end of the hood is lifted to provide a gap between the hood and an engine compartment or room so that the hood can deform downward to thereby absorb collision energy. In the hood apparatus, the collision of the vehicle with the obstacle is detected by a collision sensor. Based on a collision signal output from the collision sensor, a control unit actuates a rod of a hood lifting/retaining mechanism to ascend to cause a flexible link mechanism to extend or stretch out to thereby lift a rear end of the hood so that a gap is provided between the hood and the engine room.
In the proposed vehicle hood apparatus, the rod has a hook for preventing downward movement of the rod upon arrival of the rod at its elevated or lifted position. The hook is rotatably attached to the rod by means of a support pin and is urged to extend outwardly from the rod by a compression spring. When the rod is elevated to its lifted position, the hook projects outwardly to lockingly engage with a vehicle body to thereby inhibit downward movement of the rod.
For retaining the hood at its lifted position, the vehicle hood apparatus has a complex hook-locking mechanism comprised of the compression spring and the hook, as explained above, which mechanism may be provided on the rod or built in the vehicle body. However, the hook-locking mechanism built in the rod makes the overall arrangement of the hood lifting/retaining mechanism complex and undesirably large in size. Further, the arrangement in which the hook-locking mechanism is built in the vehicle body requires due care to be taken for securely hook-locking the rod when the rod, which moves at an extremely high speed, is elevated a predetermined amount.